Pyrolytic Graphite (HT) grade is similar to Substrate Nucleated (SN) grade of pyrolytic graphite but is thermally annealed to increase thermal conductivity. The increase in conductivity is about four times that of PG-SN grade or more than four times better than copper. The material is deposited as graphene onto a substrate giving it a layered composition and is anisotropic. This also means it has different properties in one of the two dimensional planes. In the C place (across the layers) it has low thermal conductivity, acting as an insulator. In the A-B place (with the layers) it has very high thermal conductivity, acting as a superb conductor.